Dear Doctor: I've always loved animals, and now I want to stop eating meat. But I'm 15 years old, and my parents think that's too young to make such a big decision. What can I tell them about being a vegetarian? I'm hoping I can persuade them.

Dear Reader: We think it's admirable that you want your lifestyle to reflect your beliefs. And we also understand how taking on a new diet might cause your parents to worry. As a teenager, you're in a period of growth spurts and hormonal shifts. Poor nutrition can affect your health, moods and learning ability. It may even play a role in susceptibility to disease in adulthood.

That said, the good news is that with proper planning, a vegetarian diet can be as nutritionally complete for people of all ages as one that includes meat. The vegetarian diet is often low in saturated fat and also high in dietary fiber. As a result, studies find that vegetarians often have a lower body mass index (BMI), lower blood pressure and more healthful cholesterol levels than people who eat meat. In addition, death from heart disease, stroke, Type 2 diabetes and certain cancers is lower among vegetarians than non-vegetarians.

You and your parents should start by deciding where on the meat-free scale of eating you wish to begin. Some vegetarians include milk and eggs in their diets. Vegans avoid all animal products, including honey and gelatin. And while it's not strictly vegetarian, some individuals skip red meat and poultry, but do eat fish and seafood.

When vegetarians decide to cut milk and eggs from their diets, alternative sources of protein, calcium and B12 become necessary. Protein can be found in soy products, beans, legumes and supplements. Small amounts of calcium are available in leafy greens and almonds. To get enough of the mineral, vegans often include calcium-fortified soymilk, juice and cereals, and calcium-set tofu in their diets.

Vitamin B12, found only in animal protein, is a vital nutrient. Your body needs it to make red blood cells, for proper neurological function, and to synthesize DNA. Vegetarians can get B12 in fortified products like cereals and soymilks, as well as in supplements.

Iron is a nutrient that vegetarians and meat eaters alike can fall short on. It helps your blood carry oxygen to muscles and organs, and is important for growth and normal cell function. Heme iron, which is most easily absorbed by the body, is found in lean meat and seafood. Nuts, beans, some leafy greens and fortified grain products are sources of non-heme iron, which the body doesn't use as efficiently. Vitamin and mineral supplements can help provide adequate iron, as well as other essential nutrients.

We've just hit the high points here. If and when your parents give you the OK to say goodbye to meat, we strongly recommend that you all become students of vegetarian nutrition. Your family doctor can help, and can also guide you to some excellent books and websites to help you plot your future journey.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I'm 75 years old and have bruising on my hands, seemingly when anything touches them. I do not take blood thinners or aspirin. Occasionally I take an Aleve, which seems to make it worse.

Dear Reader: Such bruising is an annoying, yet common, problem as our bodies age. Many of my patients are flummoxed by the bruises on their skin, not even recalling any trauma that led to the purplish marks. Easy bruising as we age can be traced to several factors.

First, the distribution of fat changes. This is one of the crueler aspects of aging. Older bodies store more fat in the belly and lose the fat under the skin. This is most easily seen in the face, arms and in the back of the hands. Skin that has lost its subcutaneous fat has lost much of its cushion to absorb trauma. Without this cushion, the small blood vessels that course within and below the skin are more susceptible to direct trauma, leading to bleeding underneath the skin.

Second, the skin loses collagen, its most common protein. After the age of 20, a person produces 1 percent less collagen in the skin each year. So by the age of 75, the collagen loss is substantial. This causes the skin to become thinner and more fragile. Without this protection, the blood vessels underneath the skin are more prone to damage.

Third, the skin is less elastic. This means that the skin loses its ability to stretch and absorb external forces.

Finally, the small blood vessels within the layers of skin lose their elasticity as well. This increased fragility allows them to break with only minimal force.

To minimize the impact of these skin changes, you should be aware that the loss of elasticity and collagen are made worse by prolonged sun exposure. Using sunscreen on your arms and the backs of your hands will help to preserve the collagen and elastin within the skin. In addition, topical vitamins, such as vitamins A, E, C and B3 may also help to prevent sun damage. Lastly, smoking cigarettes also degrades collagen and elastin, so I would recommend not smoking.

You mentioned that you are not taking any blood thinners, but you are. Aleve (Naproxen) is a non-steroidal anti-inflammatory and, like all NSAIDS, thins the blood by reducing the ability of platelets to attach to one another. So that is why your symptoms are worse with Aleve. Supplements such as oral vitamin E or fish oil may also thin the blood, making you more susceptible to bruising.

If your bruising is accompanied by a reduced ability of your blood to clot -- which you would notice if you were to get a small cut -- you should consult a physician. This can occur because of blood thinners, but it can also be caused by a blood disorder.

In your case, I would recommend sun protection to the backs of your hands to decrease sun damage to the skin. Also, you should consider stopping Aleve and switching to Tylenol for pain relief; it doesn't have the same blood-thinning effect.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Readers: We've been reading your letters. Thank you for your interest in our thoughts, the humor with which you evaluate -- and sometimes chide -- us, and the passion you continue to show for health sciences and research. Your thoughts and questions are always interesting, often touching and never fail to make us think.

With that in mind, we're following up on some past columns that caused a stir with readers.

Toenail fungus: The column about toenail fungus remains a hot topic. As you may recall, this is a common infection that causes nails to thicken, darken and become malformed. The most effective treatment is an oral anti-fungal drug, such as Lamisil or Sporanox, which can come with side effects. Prescription topical treatments like the medicated nail polish Penlac or antifungal creams are also available. But whichever route you go, this can be a tough infection to beat.

Quite a few of you have offered two interesting home remedies, each of which has been the subject of several studies. Unfortunately, neither of these will actually cure the fungus. But the research agrees with you readers that the appearance of the affected nails can be improved, and the extent of the fungal damage lessened.

-- Topical treatment with tea tree oil: A natural (and quite strong-smelling) disinfectant, this essential oil is derived from the native Australian plant Melaleuca alternifolia. Readers recommend that you apply it to infected nails twice daily for at least eight weeks. For the fungus to be eradicated, the nail must grow out completely. That means results can take up to a year. Tea tree oil is widely available at health food stores and sometimes in the nutritional supplements section of your local drug store.

-- Topical treatment with Vicks VapoRub: The combination of camphor, eucalyptus oil and menthol, the three main ingredients in Vicks VapoRub, is believed to stop the growth of certain fungi. Follow the same application process as for tea tree oil. Numerous readers swear by this.

And for a bit of preventive hygiene, use rubbing alcohol on nail clippers between uses to prevent the risk of further infection.

Nosebleeds: In response to the column explaining the hows and whys of sudden nosebleeds, a reader shared a tip for individuals whose homes are heated with forced air, or who live in arid environments. She followed her physician's advice to put a dab of K-Y Jelly into each nostril at bedtime (not Vaseline, which is petroleum-based), and the nosebleeds that had plagued her stopped.

Copper pans: A reader considering the purchase of a set of unlined copper pans wondered if they pose a health risk. The answer is: It depends on what they're used for.

Copper is easily dissolved by acidic foods like tomatoes or tomato sauce, which should never be cooked or stored in copper. While small amounts of copper are considered safe, when ingested in large amounts it can cause nausea, vomiting and diarrhea.

If you do use unlined copper pots and pans, research the acidity of the foods you plan to cook in them. Or buy a couple of pretty ones and use them for decor.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)